1 Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas , Miagao, Iloilo, Philippines 2Graduate School of Science and Technology, Nagasaki University Bunkyo1-14, Nagasaki 852-8521, Japan

ABSTRACT

Batch and individual cultures of rotifer Brachionus rotundiformis and Brachionus plicatilis, respectively, were made to determine whether the addition of gamma-butyric acid (GABA) to yeast could improve their population growth and other demographic parameters. Rotifers were either fed with bakers yeast plus GABA, or with Chlorella vulgaris, or with yeast only. In batch culture experiment, 50 ind.ml-1 were stocked in glass jars with three replicates each treatment, and population growth was monitored daily. In individual culture experiment, neonates of the same age were stocked individually in 24-well polystyrene plates and the number of offspring produced daily were counted. The parent was transferred to the next well everyday until they died. The number of offspring, reproductive period, and lifespan were determined and intrinsic growth rate of natural increase (r) and net reproductive rate (Ro) were calculated. Results show that addition of GABA to yeast improved rotifer culture as shown in its higher r and Ro, longer reproductive period and lifespan.

1University of the Philippines in the Visayas, College of Fisheries and Ocean Sciences, Institute of Aquaculture, Miag-ao, Iloilo, Philippines 5023 2Faculty of Fisheries, Kagoshima University, Shimoarata 4-50-20, Kagoshima, Japan

ABSTRACT

A 12-week feeding trial was conducted to assess the potential of solvent-extracted soybean meal (SESM) as a protein source in diets for tilapia (Oreochromis niloticus). Four isonitrogenous diets (40% crude protein) were prepared with increasing substitution levels of SESM for fish meal at 0, 10, 20, and 30 % of the diet with an equivalent percentage of dietary protein at 0%, 4.4%, 8.7% and 13.1% respectively. Twenty tilapia fingerlings (initial ABW 0.5 g) were randomly placed in twelve aquaria at three replicates for each dietary treatment. Inclusion of 10 up to 20 % SESM in tilapia diet did not differ significantly in weight gain and specific growth rates (SGR) as compared to fish fed the control diet. Tilapia fed the 30% SESM diet exhibited significantly the lowest performance among the treatments. The best feed conversion ratio (FCR) and protein efficiency ratio (PER) were observed in fish fed the control and the 10 % SESM diets. Sensory taste test showed that fish fed the aforementioned test diets were more preferred over those fed diets 20 - 30 % of dietary SESM replacement for fish meal. No significant differences were observed on the carcass composition of tilapia fed the test diets.

Milkfish (Chanos chanos Forsskal) juveniles (ABW 37.0 g) were reared at varying densities of 12.5, 25, 50 and 100 fish m­3 to determine optimum and profitable stock load in the culture of milkfish in floating marine cages. ABW decreased with increasing density. Although fish at higher densities were generally smaller, survival was very high (99.3 -99.8%) and similar in all treatments. Net yield significantly increased at higher densities but the rate of increase started declining beyond the density of 50 fish m-3 corresponding to the significant decline in the specific growth rate of fish at the density of 100 fish m-3. The absence of density-dependent mortalities and the similarity of condition factor of the populations in all density levels tested showed that milkfish was tolerant of crowding thus can be cultured profitably at very high stocking densities. *pp. 17-26

Extracts of the microalga Nannochloropsis sp were screened against Vibrio harveyi in vitro. Isolation and purification of bioactive compound responsible for vibriostatic activity were also initiated. Extracts of Nannochloropsis sp. in methanol, n-hexane, ethyl acetate including the aqueous fraction showed antibacterial activities against Vibrio harveyi except the dichloromethane (DCM) fraction. Thin layer chromatography (TLC) analysis showed that extracts may contain cardiac glycosides, phenolics, terpenes, and flavonoids. When bioassayed against V. harveyi, however, only the terpenes and glycosides inhibited the growth in vitro. Terpenes and cardiac glycosides must be present together to effectively promote vibriostatic activity. There was no activity with only the cardiac glycosides present or terpenes in purified form. Several compounds were probably involved and were acting together in an additive or synergistic action on a site associated with vibriostatic activity. Nannochloropsis sp. extracts can thus serve as an alternative treatment to control luminous bacteria disease in penaeid shrimp larvae. Findings in this study may usher in a new era of controlling diseases by using microalga-derived biocompounds. *pp. 27-36

Metabolic Compounds in Lablab: Its Potential in Aquaculture

IDA G. PAHILA, SAMUEL S. ESPINO, AND LALAINE S. SOLANO

Division of Physical Sciences and Mathematics, College of Arts and Sciences U. P. in the Visayas, Miagao, Iloilo 5023, Philippines

ABSTRACT

The lablab complex from Leganes, Iloilo, Philippines predominantly composed of diatoms, Pleurosigma sp., Navicula sp., Nitzschia sp., green and blue green algae, Oscillatoria, Chlorella and Lyngbya sp. and other filamentous algae was assessed as a potential source of structurally complex chemical compounds through extraction, isolation and characterization. The presence of different chemical groups in the different extracts detected qualitatively and was ascertained by IR spectroscopy. Lablab extracts had terpenes, saponins, cardiac glycosides, phenolics, flavonoids, alkaloids, fatty acids and amino acids. The dichloromethane (DCM) fraction (moderately polar) had almost all the

compound classes. Terpene and saponin were present in all extracts, while cardiac glycoside was present in all extracts except in ethyl acetate, Phenolic and flavonoid groups were present only in DCM extract, alkaloid detected only in the ethyl acetate (EA) extract; fatty acid and amino acid in hexane, DCM and EA extracts.

*pp. 37-50

Use of Greenwater Technology as Biocontrol of Luminous Bacteria in Intensive Shrimp (Penaeus monodon) Grow-out Culture

1Brackishwater Aquaculture Center, Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Leganes 5003, Iloilo, Philippines, 2Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Leganes 5003, Iloilo, Philippines, 3Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8650, Japan

ABSTRACT

The use of tilapia greenwater as biocontrol of luminous bacteria in intensive shrimp culture was evaluated. Analyses were made in ponds with tilapia pens, ponds that were supplied with tilapia green water from the reservoir and ponds without tilapia greenwater (control). Significantly lower levels of luminous bacteria and total Vibrio counts were obtained in ponds with greenwater taken from the reservoir. Only the control ponds experienced high shrimp mortality after 50 days. Significantly higher shrimp survival was obtained in treatments that used tilapia greenwater after 150 days of culture. Shrimp production averages ranged from 7,783 to 8,163 kg/ha and was not significantly different between treatments. Mean phytoplankton density was similar among treatments. Other physico-chemical parameters were within the optimum range for shrimp culture. Results show that tilapia greenwater, whether from the reservoir or in pens installed within the ponds, enhanced growth, survival, and production of shrimps as well as improved the resistance of shrimps against luminous vibriosis. *pp. 51-60

Effects Of Different Feeding Schemes On The Morphological Conditions And Growth Performances Of Hatchery-Raised Milkfish Fry Grown To Fingerling In Brackishwater Pond

LIBERATO V. LAURETA1, LILY ANNE G. PIÑOSA1 AND HIROSHI FUSHIMI2

1Brackishwater Aquaculture Center, Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Miagao, Iloilo, 5023 Philippines 2Laboratory of Aquaculture and Stock Enhancement, Department of Marine Biotechnology, Fukuyuma University, Ohama, Innoshima, Hiroshima 722-2101, Japan

ABSTRACT

The effects of different feeding schemes were examined: 1) &quot;lab-lab&quot; only (T1); 2) &quot;lumot&quot; only (T2); 3) commercial feed only (T3), and 4) &quot;lab-lab&quot; + commercial feed (T4) on the growth and survival rates and incidence of morphological abnormalities of hatchery-raised fry reared to fingerlings in brackishwater nursery ponds. After 30 days of culture, mean survival rates ranged from 81 to 99%, and showed no significant difference among treatments. Milkfish fry grown in &quot;lab-lab&quot; ponds + fry mash (T4) have attained the highest ABW and correspondingly highest specific growth rates slightly different from fry fed &quot;lab-lab&quot; only (T1), &quot;lumot&quot; only (T2), and rationed commercial feed only (T3). Mean total occurrence rates of morphological abnormalities ranged 2.9 to 20.9% with T2 having the significantly highest percentage incidence. The highest occurrence rates of morphological abnormality was cleftbranchiostegal membrane (CBM), followed by deformed or partial to total absence of branchiostegal rays (DABr), deformed lower jaw (DLJ), and deformed operculum (DOp). *pp. 61-68

Habitat and Population Structure of the Mangrove-dwelling Mudclam, Anodontia edentula (Bivalvia: Lucinidae) in Guimaras, Philippines

MARIE FRANCES NIEVALES

1 Division of Biological Sciences, College of Arts and Sciences, UP in the Visayas, Miagao Iloilo 5023 Philippines

ABSTRACT

This study provides information on the habitat and aspects of the population biology and ecology of Anodontia edentula in Guimaras, (Western Visayas) Philippines. Two source sites, Panabolon Island (PANA) in the south and LAWI in the midwest of Guimaras island province, were studied from Dec 1997 to Dec 1998. The mudclam habitat and population structure were compared. The spatial distribution of mudclams varied from aggregated to random. Both populations were polymodal with the reproductive cohorts comprising the bulk. Reproduction and recruitment events are likely continuous more especially in LAWI. There was higher frequency (20-38%) of brooding individuals encountered continuously from June to October in the midwest population compared to the southern population where brooding was limited from April to May and made up only 6-8% of the samples. Monthly adult mortality was minimal and did not exceed 10% in both sites except in February and March 1998 in PANA. At present, there are no marked differences in mean shell length of mudclams collected and catch per unit effort (CPUE) between sites but the mean density of mudclams is higher in LAWI than in PANA when the mudclam fishery is much older in LAWI than in PANA.

*pp. 69-82

Effect of Salinity on the Life Table Demography and Population Growth of SS-type Brachionus sp. from an Enclosed Mangrove Forest

RHEA JOY CARTON 1, *, NORMA FORTES 2 AND ATSUSHI HAGIWARA3

1Brackishwater Aquaculture Center, Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Leganes, Iloilo 5003 2 Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Miag-ao, Iloilo 5023 3Graduate School of Marine Science and Technology, Nagasaki University, Bunkyo 1-14, Nagasaki 852-8131, Japan

ABSTRACT

Small Brachionus were taken from an enclosed mangrove forest in Batan, Aklan, Philippines. Clonal population was developed from one amictic egg and maintained in the laboratory using a Chlorella vulgaris-based diet. The effect of different salinity levels (15, 25 and 35 ppt) on the life table demography and population growth of the SStype Brachionus strain was determined. Brachionus were cultured individually in polystyrene wells at 300C and inoculated with 1x106 cells ml-1 Chlorella vulgaris. The number of neonates produced was counted daily and the mother transferred into another well. This was done repeatedly until the mother dies. The highest rate of intrinsic increase and fastest generation time was observed at 15 ppt. On the other hand, lifespan, fecundity, gross reproductive rate (GRR) and net reproductive rate (Ro) did not vary significantly among treatments. The significant effect of salinity on the reproductive activity of the SS-type Brachionus indicates its better adaptability to 15 ppt salinity than to higher salinity levels. *pp. 83-90

In Vivo Assay of Live Microalgae on Vibrio harveyi Co-cultured with Scylla serrata Larvae

The experiment was conducted to check the presence in live microalgae of an inhibitory substance against V. harveyi when co-cultured with Scylla serrata larvae. Zoea 3 larvae were reared until megalopa with Chaetoceros sp., Skeletonema sp., or Nannochloropsis sp., and with or without V. harveyi. There were 2 control groups, one with bacteria only and the other without bacteria and algae. Results show that by Day 3, regardless of the presence or absence of microalgae, survival rates in treatments with bacteria were significantly and slightly lower with those in treatments without bacteria. However, survival rates in the control group without bacteria and microalgae, and in treatments with Chaetoceros sp. or Skeletonema sp. (with or without bacteria) were no longer significantly different between treatments by Day 12. Treatments with Nannochloropsis sp., with or without V. harveyi, obtained the significantly highest survival. By Day 12, mortality was 100% in the control with bacteria only. The results confirm the presence of an inhibitory action on the growth of the bacteria V. harveyi and suggest an enriching and enhancing property of microalgae, especially of Nannochloropsis sp. *pp. 91-102

Aquaculture in the Philippines: An Economic and Sustainability Agent

ROMEO D. FORTES

Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, 5023 Miagao, Iloilo, Philippines

ABSTRACT

There has been a trend of increasing demand for fish and this necessitates an increase in production to preclude fish importation. Milkfish (Chanos chanos), tilapia (Tilapia spp.) and seaweeds (mostly Kappaphycus sp. and Gracilaria sp.) have been identified as the priority commodity species for aquaculture. The contribution of these species to the total fishery production has been increasing. The techniques for hatchery production of seeds of the windowpane oyster (Placuna placenta,) saddle-shaped oyster (Placuna sella) and the angel wing shell (Pholas orientalis) are now mature. Similarly, hatchery techniques for grouper (Epinephelus coiodes), sea bass (Lates calcarifer) and snapper (Lutjanus spp) are progressing very well. Those for rabbitfishes, Siganus spp, (S. guttatus and S. vermiculatus) and the spadefish, Scatophagus argus are being attempted with certain degrees of success. Hatchery production of juveniles of Scylla serrata has been successfully attained. Production of seeds of the giant freshwater prawn, Macrobrachium rosenbergii has been accomplished but its adoption is still low. Black tiger prawn (Penaeus monodon) culture is now being slowly revived. A paradigm shift in aquaculture has been recognized - from almost exclusively exploitative in nature to that of an agent of rehabilitation. *pp. 103-112

Women, Gender and Aquaculture in the Philippines IDA M. SIASON

University of the Philippines Visayas, Miagao 5023, Iloilo, Philippines

ABSTRACT

This paper attempts to review the knowledge base on women, gender and aquaculture in the Philippines. Two case studies were undertaken to characterize the participation of men and women in the culture of two different fish species. The results show distinct differences in gender participation in tasks comparing catfish farming and tilapia farming. Catfish farming was a potential source of additional income for lower income families. Both husband and wife shared the responsibility and tasks in the fish farm. In cases where the woman was not employed outside the house, fuller participation was conditional on whether the fishpond was located close to the house. Their success was hampered by limited financial resources, lack of sound technical support and threats from flood and water security. In the case of the tilapia growers, most of the participants were male. Their farms were run without assistance of their wives, who engaged purely in household work. This group had higher income levels compared to the catfish growers. Their tilapia ponds were also quite distant from their homes. Inasmuch as in most cases, it is the menfolk who were more easily employed in wage labor, the prospect of providing women with a means to augment household incomes could be met by backyard fish farming. It is recommended that local government units, academe and non-government agencies can collaborate to involve women in fish farming, following a successful model that has been tried out in Bangladesh. What is critical is that women are specifically targeted and that the necessary support is given. *pp. 113-122

Aquaculture in Thailand, both freshwater and brackish water, has shown continuous growth over the past 20 years. An increase of aquaculture production value over the same period of time further stresses the importance of this sector to the economy of the country. The issue of sustainable aquaculture has been given as a priority at the national level. Different approaches and efforts have been made by government, private sectors and farmers to sustain aquaculture, particularly the shrimp culture industry. Regulations on shrimp farming with regard to environmental impact have been in place since 1991. To meet international standard, a guideline for Good Aquaculture Practice and Code of Conduct has been implemented. A number of studies to minimize the environmental impact and to improve culture environment for sustainable shrimp culture have also been carried out by different institutes with promising results. Farmers who realize the importance of balanced pond ecosystem and the consequences of unmanaged farming system have changed their farming practices to conform to the changes and regulations.

1Faculty of Agriculture, University of Miyazaki, Miyazaki, 889-2192, Japan, 2 Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, Miag-ao, Iloilo, Philippines 5023 3 Kyushu Medical Co. Ltd, Kitakyushu, Fukuoka 803-0814, Japan

ABSTRACT

The Cypridina luciferin analogue (CLA), a highly sensitive chemiluminescence (CL) probe, was used to detect superoxide (O2-) in kuruma shrimp hemocytes. The CLA-dependent CL of the shrimp hemocyte after phorbol 12myristate 13-acetate (PMA) stimulation was inhibited by superoxide dismutase. Nitric oxide (NO) production from the shrimp hemocytes was detected by fluorometric measurement after co-stimulation with lipopolysaccharides (LPS) and

recombinant human interferon g in vitro. The supernatant of a hemocyte culture after stimulation showed an increase in fluorescence intensity, but decreased upon with addition of NG-monomethyl-L-arginine (L-NMMA). These results show that shrimp hemocytes can produce O2 and NO and these free radicals play an important role in the shrimp defense network. *pp. 135-144